The twin prime conjecture is a mathematical theory. It says that it is possible to find two twin primes that are as big as wanted.

Twin primes are prime numbers that differ by two. For example, 3 and 5 are both prime and differ by two. They are twin primes. 23 is prime, but it is not a twin prime. The primes nearest to 23 are 19 and 29. Twin primes were discovered by Euclid in 300 B.C.